The most secure system in the world is powered off, embedded in concrete, and mined with tamper-sensitive explosives. Unfortunately, it is also the most useless system in the world. In order for a system to be useful, it needs to interact with the environment and provide some level of functionality. Historically, embedded systems were mostly islands – that is, they provided their functionality in a stand-alone manner, and weren’t connected, or had limited connectivity to other systems. With these kinds of systems, it was relatively easy to analyze their security – the number of ways of getting in and compromising the operation was extremely limited. Systems today are more connected. A lot of these protocols and connections are incorporated into modern devices as a matter of course, without enough thought given to their security implications.